/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshNormals.h
NormalOverlay must be attached to ParentMesh or an exact copy
void RecomputeOverlayNormals ( const [FDynamicMeshNormalOverlay](API\Runtime\GeometryCore\DynamicMesh\FDynamicMeshNormalOverlay) * NormalOverlay, bool bWeightByArea, bool bWeightByAngle )